<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script> 
        let num1 = Number(prompt('输入第一个数'))//显式转换
        let num2 = +(prompt('输入第二个数'))//隐式转换
        let sum = num1 + num2
        alert(`两数之和为${sum}`)
    </script>
</body>
</html>